how to fix P0171 code on my Toyota Corolla E210 (2019-2024)

Solution

1. Preparation

• Gather tools and parts.
• Disconnect the negative battery terminal to ensure safety.
• Allow the engine to cool if it has been running.

2. Inspect and Repair Air Intake System

• Tools Required: Socket set, screwdrivers, vacuum gauge
• Inspect all intake hoses for cracks or disconnections.
• Tighten or replace any loose or damaged hoses.
• Check the intake manifold gasket for leaks and replace if necessary.

3. Test and Clean the MAF Sensor

• Tools Required: MAF sensor cleaner (isopropyl alcohol or specialized cleaner)
• Remove the MAF sensor from the intake duct.
• Spray the MAF sensor with cleaner and allow it to dry completely before reinstalling.
• Reinstall the MAF sensor and ensure it is secured properly.

4. Check Fuel Pressure

• Tools Required: Fuel pressure gauge
• Locate the fuel rail test port and connect the fuel pressure gauge.
• Turn the ignition to the "ON" position without starting the engine to check the fuel pressure reading.
• If the pressure is below specifications, inspect the fuel pump and replace it if necessary.

5. Inspect and Test Fuel Injectors

• Tools Required: Noid light or multimeter
• Disconnect the fuel injector connectors.
• Use a noid light to check for proper electrical signals to the injectors.
• If signals are absent, inspect the wiring harness and ECM.
• If injectors are clogged, remove them and clean or replace as necessary.

6. Replace Oxygen Sensors (if necessary)

• If oxygen sensors are found to be faulty during diagnostics, replace them according to the manufacturer's specifications.
• Tools Required: O2 sensor socket, torque wrench
• Disconnect the old sensor, install the new one, and torque to manufacturer's specifications.